Why is HST so much better then gear drives...

_RaT_ · Jul 22, 2004

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dass · Jul 22, 2004

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To20Chris · Jul 22, 2004

NO NO NO! We must conclusively prove that HST is utterly worthless, and then make everyone agree!

Or, maybe not. /forums/images/graemlins/smirk.gif

_RaT_ · Jul 22, 2004

There are those out there that wish you were correct. I just chalk myself up as one of those that owns both a gear and HST and must too stupid to know any better. Ignornace is bliss. But I am happy! /forums/images/graemlins/grin.gif

KiotiJohn · Jul 22, 2004

</font><font color="blue" class="small">( There are those out there that wish you were correct. I just chalk myself up as one of those that owns both a gear and HST and must too stupid to know any better. Ignornace is bliss. But I am happy! )</font>
And I chalk myself up as one who has had gear, has HST, and wants to add a synchro shuttle tranny to the stable. It's all good. John

_RaT_ · Jul 22, 2004

The shuttle really is a great way to go as well. Most of my time is on a Kubota L4850 5 cylinder 8X8 with a shuttle. After that, a NH 2120 12X12 with shuttle. My experience with HST between my L48 and L3830 is only about 500 hours now.

Moon · Jul 23, 2004

I skipped over this thread at first, thinking it would be the same old stuff .... Curiosity got the better of me and I'm happy to see this discussion has not gone the way that many have. No bashing from either side. Very cool. Good job guys!
Moon of Ohio

Rowski · Jul 24, 2004

Does anybody know if a hydraulic shuttle runs as hot as a hst? Seems to me like it would be between a gear and hst. I know on my TN spec they bump up the gpm by almost 5 gpm and add a cooler if you go the hydraulic shuttle.

timb · Jul 24, 2004

I believe most of the extra heat in an hst comes from fluid sheer in the slippage between pump and motor. That hp loss just doesn't evaporate - you've got the equivalent of a 1500-2500 watt heater helping heat that fluid. (2-3 1/2 hp loss).

Once a shuttle is locked up forward or reverse it should be in basic mechanical drive mode - no slippage, no extra heat. There is work for the hydraulics to do getting in to or out of gear but should be the same as a basic (i.e. collar-shift) manual tranny once in.

How long before some manufacturer combines an hst with (wrong specific item but for lack of a better term) 'lock-up torque converter' like modern auto trannys in cars? Seems like you could get most of the good of both approaches in one tranny. Steady pull - straight through lock up - soon as you dicate speed change - let 'er go normal hst.